LONDON, Oct 12 (Reuters) - UBS is investigating a second accusation of sexual assault made by a former junior trader who said the Swiss bank had failed to deal appropriately with a previous, separate rape allegation, two sources told Reuters.

UBS began a review in July into how it handled the former employee's initial allegation that she was raped in September 2017 by a senior colleague, the sources, who have direct knowledge of the matter, said.

As part of that review, the bank is investigating claims by the woman that she was also groped almost a month before by another employee, a managing director, the sources said.

UBS has hired an external law firm to help with the investigation, the sources said.

"Our ongoing review covers all the allegations made. We remain confident in our policies and processes for handling such matters, but until the review is finalised it wouldn't be appropriate to comment any further," a UBS spokeswoman said.

The woman and the senior employee accused of raping her have since left UBS. The woman said she made a police complaint about the alleged rape. London's Metropolitan Police confirmed they were investigating the incident.

UBS declined to provide information on the former employee accused of rape. Reuters attempted to contact the individual via social media but was unable to get a response.

The managing director accused of groping still works for the bank. In an email, he referred Reuters questions to his lawyers. His lawyers said he denied the allegations.

"He denies the underlying allegation in the strongest possible terms, and considers such conduct abhorrent, and was not aware there was any investigation until today," the law firm representing him, Himsworth Scott, said in an email to Reuters on Oct. 10.

"Our client is limited in his ability to respond to the underlying allegation by virtue of his duties of confidentiality to his employer, however suffice to say there are robust grounds on which he will demonstrate the implausibility of the allegation and his supportive relationship with the junior trader concerned."

A global push for greater exposure and prosecution of sexual misconduct followed a wave of allegations which began to emerge last year in the global film and entertainment industry, spawning the high-profile #MeToo movement in its wake.

Relatively few financial services workers have gone public with allegations of sexual crimes.

The former UBS trader, who now works for another bank and declined to be named, alleges she was touched inappropriately by the managing director at an evening event in August, weeks before her alleged rape. She told Reuters she did not report the groping incident at the time because she felt it was a less serious transgression and she feared reprisal at work.

"I chose not to report it because the retaliation would have been unbearable, and I wanted them to take my main assault more seriously," she said.

The woman said UBS allowed the man she accuses of rape to work in close proximity to her for almost a month after she reported the allegation. The bank then suspended him pending investigation, but the woman said it failed to complete its investigation before he resigned in March.

UBS has "a zero tolerance" policy on sexual misconduct and harassment and immediately investigates all allegations, the spokeswoman said.

"Our first priority is always to support our people and provide a safe environment to report any misconduct. Following significant cases, we conduct a review and if there are opportunities to strengthen our procedures we do so," she said.

The ex-employee has shared her complaints with the Financial Conduct Authority, Britain's financial services watchdog. The FCA did not immediately respond to a request for comment. (Editing by Nick Tattersall and Silvia Aloisi)